I believe that the Mac Mini uses a notebook hard drive. If so, then the one in my MacBook Pro stays cool, and we've had over 100F temperatures in the past couple of days. So, the Mac Mini should overall operate much cooler than my MBP.

I've got 2 mac mini's in my data center doing outbound mail - the ambient inlet temp is in the 71-74 degree F range and snmp reports the outlet temp is only about 90 degrees - an air temperature change of 20 degrees F seems to be the average so, with high end tolerances above 110 you could get away with 90+ degree F inlet. Ours have regular notebook harddrives and don't get too hot. Again, I'm just using them to send out mail, not a whole lot of reading going on, but S.M.A.R.T. is reporting that the drive temperature averages 86 degrees F.